The present invention relates to a device for electrical contact between an electrical supply and a layer of flexible fibrous conductive material and the use of this device for heating by the Joule effect.
When it is desired to supply with electrical current ohmic conductive materials of the fibrous type, such as cloths, felts, composite needled materials, of carbon (activated or not), their structure, their surface condition and the absence of rigidity do not permit using conventional electrical contact techniques. Thus, it is not possible to provide directly points of soldering on their surface. It is also difficult to use screws or rivets without damaging the fibrous material, or altering its mechanical strength. For example, metallic clamps can give rise to tearing of the layer of fibrous material under the influence of tension or mechanical traction.
It is also not possible to use contacts of the rigid copper bar type with which it is difficult to control the pressure exerted on the fibrous material, nor to shape this latter. Moreover, such bars provide only weak contact with the irregular surface of the fibers of conductive material that it is desired to connect to an electrical supply. These drawbacks are amplified when the fibrous material, generally supple and very flexible, is of small thickness.
Moreover, in the case in which it is necessary to give to the layer of conductive material a non-planar shape, for example a curved or folded shape, it is also difficult to obtain continuous electrical contact over large lengths. This is particularly the case when said material is used for heating by the Joule effect, for which heating must be as homogeneous as possible, hence one should obtain the most homogeneous possible distribution of current in the cloth over all the length of the contact. The result of this effect will give a current transmission as homogeneous as possible over all the surface of the material extending between the two electrical contacts.